The thermostat sets the minimum coolant temp. As long as it is functioning properly, it has nothing to do with the maximum temp.
If it overheats below about 30 mph this is a heat shedding issue, the rad is not shedding it fast enough. Since at this time, it is the fans job to get the air through the rad, that is the first go-to. Of course the rad has to be sealed to the core and to the hood so air cannot sneak around the sides and come back for a second trip which will do nothing but make the issue worse. And finally, the air has to have somewhere to go after it comes thru the rad.
I have the same combo, namely; 360+.040, Eddies, AG, and Headers. My rad is a 1973 A/C rad.Hyup 45 years old this year, and I've had it since the late 70s; I was second owner of that old moredoor,lol.
But I run a hi-flow pump and stat plus a 7 blade steel fan with a thermostatic fan-clutch. I run a 7psi cap, and a 205*hi-flo stat., and fresh cold air into the carb. I also ventilated the hood so that the hot air has somewhere to go when I shut it off. I have zero heating issues,zero.
It's been like that since 2004,about 100,000 miles.
But I'll tell you a secret; KB says to run those KB 107s on the street at .0015 to .002 skirt clearance, and the engine kept locking up every time I shut it off, even with a 195 stat.
Well easy solution, I had the cylinders honed out a tad more.I think I am at .0025. I'll take the early morning rattle thank you very much;it only lasts for a few seconds during warm-up.
And finally, my combo (4-speed/3.55s and a 230*cam) likes advance of 12 to 14 initial. I run a two-stage curve with a kink at 2800, where it runs 28*. Full timing comes in at about 3400=32/34*. With this curve I run 87E10 at 10.9Scr. I have run it at up to 185psi, still on 87E10.
With an automatic, you can run more initial, and with a hi-stall wouldn't need the kink. But if your all-in is too early, you won't be able to run 87....... unless it's higher than 3400,lol.
Happy HotRodding
PS
I'm not gonna tell you to get rid of the electric fan,lol, unlike some other guys on here always do..... But you couldn't give me one. On the street it makes very little sense to me. If it pukes you are walking. Go mechanical and carry a spare belt. My Milodon pump has over 100,000 miles on it. Cheapest pump, in the long haul, that I ever bought. In Canada it cost me over $150 delivered,yet when the time comes, I will for sure get another.
Ok, I confess, I am that guy, lol.
And here's why; On the street that cooling system is in a constant mode of working hard. So you are running the alternator to supply the power to run the fan, and sucking the battery down whenever the alt cannot do it by itself. What's wrong with that picture? You know the alternator is not very efficient at converting energy right? Some say about 20%. So you are just trading a couple of HP that would be required to run the fan on the street, for several times more HP to run the electrics.And in the meantime, these issues keep popping up. If you lose an engine, it's gonna be a bit irritating. So I say run a thermostatic fan-clutch, on a big 7 blader,with a matching shroud, and IMO, the majority of your problems will be over. The hi flows, the drive ratio, and CAI,are icing.
